A simple case of borders, where all sides are the same color, are DOUBLE style, and don't have rounded corners, can easily be optimized to avoid using expensive transparency layers.
Created attachment 136829 [details] Patch
Comment on attachment 136829 [details] Patch Attachment 136829 [details] did not pass chromium-ews (chromium-xvfb): Output: http://queues.webkit.org/results/12391249
Created attachment 136831 [details] Patch
Comment on attachment 136831 [details] Patch Clearing flags on attachment: 136831 Committed r113991: <http://trac.webkit.org/changeset/113991>
All reviewed patches have been landed. Closing bug.